1. Field of the Invention
The present invention relates to a high performance solid rocket propellant and, more particularly, to an ammonium nitrate propellant having greatly reduced hydrogen chloride emissions.
2. Description of the Prior Art
Recently there was considerable concern that the cumulative quantity of HCl gas which would be emitted into the stratosphere from the solid propellant would be sufficient to possibly create a potentially serious hazard to life on earth, particularly to humans. The concern arose from the fact that the conventional ammonium perchlorate baseline propellant normally utilized in rocket motors and boosters produces an exhaust during burn which contains between 21 and 22 weight percent HCl gas. The concern was that this quantity of HCl released into the stratosphere may be sufficient to disrupt the natural ultra violet radiation shield in the stratosphere. The theory being that the chlorine from the exhaust could catalytically deplete the ozone in the stratosphere to the point where a health hazard could result for people here on earth from the increase in the ultra violet radiation reaching the earths surface. For the Space Shuttle and other future aerospace flights, a propellant performance specification goal has been suggested which would keep HCl in the exhaust at or below about 3% level. An environmentally acceptable high performance propellant with zero or minimal HCl emissions has long been desired.
Propellants containing ammonium nitrate (AN) as oxidizer do not produce the objectionable hydrogen chloride emissions. However, in most previous AN propellants the highest solids loading has been 78-80% in order to have a workable master-batch for casting a motor and the highest reported solids loading has been at about 82%. Furthermore, AN propellants usually have burning rates of about 0.1 in/sec at 1000 psia which is a factor of three times below the specification for the Space Shuttle propulsion system.